TLDR Human hair has a new region with ordered filaments and the cuticle contains β-keratin sheets.
The study revealed a new region in the cortex of human hair near the cuticle boundary where intermediate filaments (IFs) are both aligned with the hair's axis and orientationally ordered in-plane, a contrast to the disordered IF arrangement deeper in the cortex. Additionally, the cuticle was found to contain β-keratin sheets instead of α-keratin, as indicated by the absence of a key diffraction feature. This research underscored the utility of sub-micron x-ray beams in examining the structures of complex, multi-phase systems.
55 citations
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February 2014 in “Journal of Structural Biology” Human hair has a complex, variable structure with a consistent matrix and double-twist pattern.
15 citations
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May 2013 in “International Journal of Cosmetic Science” Different ethnic hair types have unique nanoscopic and molecular features despite having the same basic keratin structure.
62 citations
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December 2008 in “Journal of structural biology” Hair curvature in Japanese people is linked to specific cell types and filament arrangements in the hair cortex.
65 citations
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May 2006 in “Journal of Structural Biology” Hair curliness is due to uneven distribution of different cortices within the hair fiber.
22 citations
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January 2006 in “Journal of Structural Biology” 66 citations
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June 2004 in “Biophysical Journal” 
31 citations
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December 2002 in “Biochimica et biophysica acta. G, General subjects/Biochimica et biophysica acta. General subjects (Online)” The research found two types of calcium in human hair, one that varies among individuals and another that is consistent across people.
48 citations
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January 2002 in “Journal of Structural Biology” 53 citations
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September 1999 in “Journal of Synchrotron Radiation” 63 citations
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December 1998 in “Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology” 
191 citations
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November 1959 in “Annals of the New York Academy of Sciences” Hair and wool have complex microscopic structures with microfibrils and varying cystine content.
March 2010 in “Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature” Beard hair medulla cells have a unique and varied keratin pattern.
87 citations
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July 2009 in “The journal of investigative dermatology/Journal of investigative dermatology” Human beard hair medulla contains a unique and complex mix of keratins not found in other human tissues.
1 citations
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August 1981 in “The Journal of Dermatology”
